Optical systems and methods and optical amplifiers for use therein

Abstract

Optical transmission systems of the present invention include at least one optical amplifier in which pump power being provided to an amplifying medium is amplified using a pump amplifier prior to being introduced into the amplifying medium. In various embodiments, a cascaded Raman resonator is used as a pump booster source to provide Raman amplification of the pump power being supplied from one or more pump sources to the signal channel amplifying medium.

What is claimed is:  
     
       1. An optical amplifier comprising: 
       an optical fiber medium;  
       a pump that supplies optical power in at least one pump wavelength in the optical fiber medium;  
       a pump amplifier that amplifies the pump optical power before the pump optical power is introduced into the optical fiber medium, wherein the pump amplifier comprises:  
       a pump amplifying fiber connected between the pump and optical fiber medium;  
       a pump booster source connected to the pump amplifying fiber comprising an optical power source and a cascaded Raman resonator, wherein the cascaded Raman resonator further comprises:  
       an input wavelength combiner having first, second, and third input wavelength ports;  
       an output wavelength combiner having first, second, and third output wavelength ports; and,  
       a Raman gain medium optically connecting the first and second input wavelength combiner ports with the first and second output wavelength combiner ports to form a Raman resonator cavity, wherein the pump booster power exits the Raman resonator cavity at the output wavelength through the third output wavelength port and optical power is introduced through the third input wavelength port into the Raman resonator cavity.  
     
     
       2. The optical amplifier of  claim 1 , wherein the optical power source is a semiconductor diode. 
     
     
       3. The optical amplifier of  claim 1 , wherein the optical power source includes a plurality of semiconductor diodes. 
     
     
       4. The optical amplifier of  claim 3 , wherein the high power semiconductor diodes all produce optical power at a common wavelength. 
     
     
       5. The optical amplifier of  claim 3 , wherein the semiconductor diodes each produce optical power at a wavelength different then that produced by each other diode. 
     
     
       6. The optical amplifier of  claim 3 , wherein the input wavelength combiner includes a 2×2 WDM coupler having first, second, third, and fourth input wavelength ports. 
     
     
       7. The optical amplifier of  claim 3 , wherein the output wavelength combiner includes a 2×2 WDM coupler having first, second, third, and fourth output wavelength ports. 
     
     
       8. The optical amplifier of  claim 6 , wherein the fourth input wavelength port is optically connected to a high reflectivity input reflector positioned to reflect input wavelength optical power exiting the Raman cavity through the fourth input wavelength port back into the Raman cavity. 
     
     
       9. The optical amplifier of  claim 8 , wherein the reflector includes a fiber Bragg grating. 
     
     
       10. The optical amplifier of  claim 7 , wherein the fourth output wavelength port is optically connected to a high reflectivity output reflector positioned to reflect output wavelength optical power exiting the Raman cavity through the fourth output wavelength port back into the Raman cavity. 
     
     
       11. The optical amplifier of  claim 10 , wherein the reflector includes a fiber Bragg grating. 
     
     
       12. The optical amplifier of  claim 3 , wherein the third output wavelength port is optically connected to a low reflectivity output reflector positioned to reflect a portion of the pump booster power in the output wavelength exiting the Raman cavity through the fourth output wavelength port back into the Raman cavity. 
     
     
       13. The optical amplifier of  claim 12 , wherein the reflector includes a fiber Bragg grating. 
     
     
       14. The optical amplifier of  claim 3 , wherein the optical fiber medium is a Raman amplification medium. 
     
     
       15. The optical amplifier of  claim 3 , wherein the optical fiber medium is doped with rare earth elements. 
     
     
       16. The optical amplifier of  claim 3 , wherein the pump co-pumps the optical fiber medium. 
     
     
       17. The optical amplifier of  claim 3 , wherein the pump counter-pumps the optical fiber medium. 
     
     
       18. The optical amplifier of  claim 3 , wherein the pump booster source co-pumps the pump amplifying fiber. 
     
     
       19. The optical amplifier of  claim 3 , wherein the pump booster source counter-pumps the pump amplifying fiber. 
     
     
       20. The optical amplfier of  claim 3 , wherein: 
       the input wavelength combiner includes at least a 2×2 WDM coupler having first, second, third, and fourth input wavelength ports;  
       the fourth input wavelength port is optically connected to a high reflectivity input reflector positioned to reflect input wavelength optical energy exiting the Raman cavity through the fourth input wavelength port back into the Raman cavity;  
       the output wavelength combiner includes at least a 2×2 WDM coupler having first, second, third, and fourth output wavelength ports;  
       the fourth output wavelength port is optically connected to a high reflectivity output reflector positioned to reflect output wavelength optical energy exiting the Raman cavity through the fourth output wavelength port back into the Raman cavity; and,  
       the third output wavelength port is optically connected to a low reflectivity output reflector positioned to reflect a portion of the pump booster power in the output wavelength exiting the Raman cavity through the fourth output wavelength port back into the Raman cavity.